1. Field of the Invention
This invention pertains to hot beverage brewing apparatus. More specifically, it pertains to a filter for use in a brew cup used in such apparatus, whereby substantially all of the spent grounds and fines are discarded after the brewing operation has taken place.
2. Description of Prior Art
This improved filter is intended for use in a brew cup and brewing machine of the type described in U.S. Pat. No. 3,483,811, issued to Heier. This patent shows an apparatus which contains several stations including:
1. A DISPENSING STATION FOR DISCHARGING A PREDETERMINED QUANTITY OF PARTICULATE SOLIDS SUCH AS, FOR EXAMPLE, GROUND COFFEE;
2. A BREWING OR INFUSION STATION AT WHICH A PREDETERMINED QUANTITY OF HOT WATER MAY BE DISPENSED AND INFUSED THROUGH THE SOLIDS TO YIELD THE HOT BEVERAGE; AND
3. A DUMPING STATION FOR DISPOSING SPENT SOLIDS FROM THE BREW CUP.
The filter of the present invention is used with a brew cup similar to that shown in the Heier patent. That patent does not teach a use of any filter whatsoever in the brew cup, the separation of the grounds from the finished product being accomplished solely by means of an apertured plate connected to the top of the guide spider. In such an arrangement, the grounds and fines often cake up on the plate and cannot be readily removed. Also, the grounds are able to work their way around the edges of the plate and find their way into the finished drink. Both the cleaning and the replacement of the plate are time consuming, difficult and costly. The filter of the present invention avoids all of these problems.
Other prior art filters have not been effective in alleviating these problems. It has been suggested that individual sheets of filter paper be used in brewing each cup of coffee. However, this has been unacceptable because of the expense thereof and because of the complexity of the mechanism for feeding and removing the individual sheets of filter paper.
It has also been suggested that a stainless steel electroetched filter be utilized. While this has proven generally satisfactory, the stainless steel filter is expensive and must be cleaned periodically. Some fines still become clogged in the filter.
It has been further suggested that a nylon filter be used in combination with a stainless steel electro-etched filter. However, neither the expense of the electro-etched filter nor the tendency of the fines to clog the combined nylon and stainless steel filters is eliminated. Caking of the grounds and channeling of the water through particular areas of the grounds are also a problem in these devices.
U.S. Pat. No. 3,651,947, issued to Schollhamer and assigned to the assignee of the present invention, teaches an improved filtering means comprising a nylon or dacron filter disposed over a mesh stainless steel screen. While this filter is excellent in use, it is a stationary filter that is not subject to vertical movement. Accordingly, this filter could not be used although it is desirable that the same filter element be used.
The filter of the present invention obviates not only the problem of channeling and caking but also prevents substantially all grounds or fines from reaching the finished beverage. In addition, the filter has a self-cleaning feature that increases both the life and utility of the filter.